Gossen Metrawatt GmbH
41
14
Important Basic Information on Tests and
Measurements
14.1
Important Safety Information
Observe and comply with the following safety information when
performing individual measurements and test sequences.
14.1.1 Switching Loads – Maximum Starting Current
The test instruments permit
active
testing of DUTs with a nominal
current (load current) of up to 16 A.
The test socket on the respective test instrument is equipped with
16 A fuses to this end, and the switching capacity of the internal
relays is also 16 A. Starting current of up to 30 A is permissible.
Attention!
!
Despite extensive protective measures targeted at pre-
venting overloading, the relay contacts may be welded
together if
starting current exceeds 30 A
.
Follow the procedure described below and observe in-
formation concerning defective relays.
Procedure
Be absolutely sure to adhere to the sequence specified below
when switching the live device under test. This prevents excessive
wear of the mains relays at the test instrument.
Before measurement:
1
Device under test
: Turn the DUT off via its own switch.
2
Test instrument
: Switch line voltage to the test socket.
3
Device under test
: Turn the DUT on via its own switch.
Perform the measurement.
After measurement:
4
Device under test
: Turn the DUT off via its own switch.
5
Test instrument
: Deactivate line voltage to the test socket.
Safer Testing with Test Adapter
In the case of test objects for which a starting current of greater
than 30 A can be expected, we urgently recommend the use of a
test adapter for larger starting currents:
for example test adapters from the AT3 series
(AT3-IIIE, AT3-IIS, AT3-IIS32, AT16DI or AT32DI).
Alternative: Passive Test
If necessary on the basis of the hazard assessment, testing can
be conducted as a passive test (equivalent leakage current
method), i.e. without switching line voltage to the test socket.
Defective Relay (“L(N) test socket fuse defective”)
If the following error message is displayed, the fuses and/or relays
are defective:
“
L(N) test socket fuse defective
”.
➭
Check both of the mains connection’s fuse links. If they’re de-
fective replace them with new ones.
➭
If the error message described above still appears, it must be
assumed that the relay is defective. If this is the case, the test
instrument must be sent to our service department for repair
(see section 22 “Contact, Support and Service”).
14.2
Measurement with DUT Connected to Line Voltage
Attention!
!
Dangerous Touch Voltage!
Exposed parts may conduct dangerous touch voltage
during testing.
Do not touch under any circumstances!
Use a special cover in order to avoid touch contact.
Mains power is disconnected by the instrument if leakage current
exceeds approximately 10 mA (can also be set to 30 mA) (see
section 13.2 “Residual Current Monitoring”). However, this does
not fulfill the requirements specified for a PRCD.
Attention!
!
If the “PROCEED in case of limit violation” setting is
used, enhanced safeguarding against touch contact and
a 30 mA RCD must be used, and personal protective
equipment (PPE) must be worn (secure workstation).
Attention!
!
The function test may only be performed after the DUT has
successfully passed the safety test!
14.3
Measurement of Insulation Resistance and Equivalent Leakage
Current
(alternative leakage current measuring method)
Attention!
!
Electric Shock! Risk of Consequential Accidents!
Testing is conducted with up to 500 V. If terminals L or N
at the test socket or the test probe are touched, electric
shock may occur which could result in consequential ac-
cidents (despite current limiting for the test to < 3.5 mA).
Do not touch terminals L or N at the test socket or the
test probe.
14.3.1 Measurements in IT Systems
The
IT system
setting can be
activated for all
single measure-
ments and test sequences with the rotary switch in the
SETUP
position (Setup 1/3) via the
All Measurements
submenu (in this case
the
icon appears in the header of each display page):
with
“Meas. at IT Mains” set to Yes:
active leakage current measure-
ments (or all measurements with reference to PE at the mains
connection side) are disabled. Test sequences which include
measurements of this sort are also disabled.
If, when being connected to line voltage, the test instrument
detects a change at PE as compared with the previously used
mains connection, the inspector is asked immediately after
startup if the currently used outlet belongs to an IT system. The IT
system option in SETUP is activated based on the user’s answer.
If “Meas. at IT Mains” is activated, this is indicated by the
icon
in the header.
Regardless of this, it’s always possible to change the option man-
ually in
SETUP.
The setting for the “Meas. at IT Mains” option is retained even
after disconnection from the mains.
In IT systems, active leakage current measurements (or any mea-
surements with reference to PE at the mains connection side) do
not deliver reliable measured values, for which reason all single
measurements of this sort, as well as test sequences which
include this type of measurement, are disabled when the “Meas.
at IT Mains” option has been activated in
SETUP
.
The
Meas. at IT Mains
parameter can be set in Setup:
Setup 1/3 > All Measurements >
Meas. at IT Mains
When selecting
between two
states: direct
change without
submenu
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